Apparatus for distilling liquids



July 29, 1969 E vlNCENT ET AL I 3,458,404

APPARATUS FOR DISTILLING LIQUIDS Filed Dec. 11. 1967 4 Sheets-Sheet 1 23 Q2 3|\ 1 2| 34 34 24 27 32 A 'q I 26 v as I 9 I9 u 3| j 3 l8 E o 28 36 3 64 4 32 8 8 FIG. 2

2a 1 66 55;. i le rifl 7 7 4 2 5 l2 L 4 5 45 E l6 FIG 43 u B: if I 56) L a \57 II l7 al .l 4 y Min i: 1 59 F f i 58 i m 1 INVENTORSZ R. E. VINCENT FI(.

c. e. COLLINS N. H. SNYDER F. 8. WEST THEIR ATTORNEY July 29, 1969 R. E. VINCENT T APPARATUS FOR DISTILLING LIQUIDS 4 Sheets-Sheet 2 Filed Dec. 11. 1967 F I G. 3

s R O T N E V N R. E. VINCENT c. e. COLLINS N. H. SNYDER F. 5. WEST THEIR ATTORNEY July 29,- 1969 R v cg -r ET AL 3,458,404

APPARATUS FOR DISTILLING LIQUIDS Filed Dec. 11, 1967 ,4 Sheets-Sheet 5 1 1 l ii 4 a If L N v! 3 I Y E w I \Y 1 1 e H s. '6 i 1 I M j x l I l '5 \w t 1 FIG. IO

FIG. 6

INVENTORSZ R. E. VINCENT c. G. COLLINS N. H. SNYDER F. 8. WEST aw zwg BM THEIR ATTORNEY July 29, 19 69 v R VlNCENT ET AL 3,458,404

APPARATUS FOR DISTILLING LIQUIDS Filed Dec. 11, 1967 4 Sheets-Sheet 4 FIG. 9 INVENTORSZ R. E. VINCENT c. e. COLLINS N. H. SNYDER F. 8. WEST BY: ,X 96M THEIR ATTORNEY United States Patent O 3,453,404 APPARATUS FOR DISTILLING LIQUIDS Robert E. Vincent, Lafayette, Calif, Charles G. Collins, Baton Rouge, Lau, and Nate H. Snyder, El Cerrito, and Frank B. West, Berkeley, Calif., assignors to Shell Oil Company, New York, N.Y., a corporation of Delaware Filed Dec. 11, 1967, Ser. No. 689,683 Int. Cl. Btlld 3/04 US. Cl. 202176 8 Claims ABSTRACT OF THE DISCLOSURE Apparatus for distilling a distillable material by introducing the distillable material into the apparatus, heating the material, separating the evaporated vapor from the material and deentraining the separated vapors so that heavy ends and catalyst materials are knocked out and are removed through a residue outlet. The deentrained vapor is condensed and the liquid condensed therefrom is drained off.

BACKGROUND OF THE INVENTION Field of the invention-The invention relates to distillation apparatus. More particularly, it relates to apparatus for distilling liquid in the form of thin films without the necessity of physical agitation of the liquid.

Description of the prior art.-It is Well known that there are several major problems limiting yields in distillation methods and apparatuses, particularly in vacuum flashing operations and apparatuses. One of the major problems involves the adequate separation of liquid from the flashed vapors. Another of the problems involves the realization of minimum flash zone pressures. In conventional horizontal or even vertically cylindrical vacuum flash towers, the flashed vapor flows a substantial distance from the flash zone to the condensing zone in a direction of flow which is normal to the vessel cross-sectional area. That is, the vapors are caused to flow axially in the vessel. The maximum quantity of total flashed vapor in the conventional vacuum flash tower is, therefore, limited by the cross-sectional area of the tower since flash zone pressure and the quantity of entrained liquid will increase with increasing vapor velocity.

One such prior art evaporator is the so-called wipedfilm evaporator as, for example, that disclosed in a Patent No. 2,955,990 to Smith. However, these evaporators are relatively expensive in both initial cost and maintenance. Such evaporators must be operated at relatively high pressures so as to obtain a satisfactory evaporation rate.

SUMMARY OF THE INVENTION It is an object of this invention to provide generally improved and more satisfactory distillation apparatus, especially apparatus applicable to distillation of thin films of liquid.

Another object is to provide improved apparatus for distilling liquids, such as crude product alcohols.

A further object is to provide distillation apparatus comprising an evaporator that distills without the necessity of internal moving parts.

These objects are attained, according to the present invention, by providing a still, preferably of upright cylindrical form, in which the distilland or liquid to be distilled is introduced into the top of the still chamber so as to flow over a distributor tray arranged approximately horizontally. During the flow over this tray, the final degassing of the distilland occurs. The distilland then flows through a slotted distributor skirt surrounding the distributor tray and along the cylindrical side walls of the still chamber, near the top thereof, and down the side walls. Since the Patented July 29, 1969 side walls are externally heated, evaporated vapor leaves the wall horizontally and flows upward over an internal condenser towards a vacuum outlet. En route, the vapor is de-entrained through a pair of reversing channels where heavy ends and catalyst materials are knocked out and fall or flow down the channels to a residue outlet.-The de-entrained vapor is condensed on an internal condenser containing a large heat exchange surface. The condensed liquid, such as alcohol, flows down the condenser and falls into a drain leading to an evaporator product accumulator.

The apparatus of this invention operate at relatively low pressures with satisfactory evaporation rates. Entrainment is very low, resulting in almost total catalyst removal. Since the apparatus of the invention has no moving parts, it is intrinsically cheaper to operate and maintain than conventional evaporators.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a vertical sectional view taken centrally through a still in accordance with a preferred embodiment of the invention;

FIGURES 2 and 3 are sectional elevational views of details of the still of FIGURE 1;

FIGURE 4 is a partial plan view of a detail of FIG- URE 3 taken along line 44 of FIGURE 3;

FIGURE 5 is a top plan view of the flow pattern of liquid on the tray of FIGURES 3 and 4;

FIGURE 6 is a partial perspective cutaway view showing an internal portion of the still of FIGURE 1;

FIGURE 7 is a sectional view taken along lines 7-7 of FIGURE 1;

FIGURE 8 is a sectional View taken along lines 8-8 of FIGURE 1;

FIGURE 9 is a sectional view taken along line 99 of FIGURE 8;

FIGURE 10 is a vertical sectional view of a detail of FIGURE 7; and

FIGURE 11 is a plan view showing the configuration of a detail of FIGURE 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIGURE 1, the still according to a preferred embodiment of the present invention comprises a still body or chamber 11 which is in general of upright cylindrical form, having a cylindrical side wall 12 and an elliptical head 13.

These parts, resting upon an elliptical head 14, are integrally joined together in a pressure-tight relationship as is well known in the art.

The bottom member 14 is supported permanently in stationary position by any suitable supporting means, such as skirt 14a, and it in turn serves to support the upper still structure including the upright cylindrical side wall 12.

The vertical cylindrical Wall 12 constitutes the hot wall or evaporating surface of the still, and is heated by suitable means, such as electrical heaters wound around the outside or otherwise cooperating externally with the wall 12, or preferably by one or more heating jackets 15 externally surrounding the wall 12 and supplied with heating fluid such as steam through entrance and exit conduits 16 and 17. Although a single heating jacket may be used, a plurality of such jackets is preferred for reasons to be discussed hereinbelow.

The top head 13 of the body 11 has a central aperture 18 through which an exchanger shell 19 extends which is sealingly fastened to top head 13. Exchanger shell 19 includes an upper head 21 having a cooling water inlet 22 and a cooling water outlet 23. Condenser head 21 is separated from shell 19 by suitable gaskets 24, disposed between corresponding flanges 25 and 26, on head portion 21 and shell 19, respectively. A vacuum vapor outlet 27 is disposed below head 21 and in communication with the interior of shell 19. A vertical, semicircular baflle 20 is welded within shell 19 and extends downward to a horizontal cross baflle 50. Battle 20 insures that all the vapor passes over the tubes on the way out as will be discussed further hereinbelow.

A liquid distributor tray 28 is substantially horizontally disposed within body 11 at the approximate juncture of top head 13 and side wall 12 and below the shell 19. Tray 28 includes a section 29, integral therewith, which is adapted to form a labyrinth seal with shell 19 and a shroud 30 mounted on shell 19 as can best be seen in FIGURE 3.

The tray 28 constitutes the degassing plate of the invention. In operation, the liquid distilland is introduced onto the top of plate 28 through a distilland inlet conduit 31 passing through the top head 13 of the still chamber 11 in tightly sealed relation therewith, and leading to a distributor 32 for inducing a smooth flow of liquid as it is deposited onto plate 28.

Distributor 32 is shown in detail in FIGURE 2. Here, distributor 32 includes an inlet pipe portion 31 having a plurality of radially extending support spokes 34 fastened or otherwise secured to pipe portion 31 and spaced a short distance vertically above tray 28. Spokes 34 center and support the sparger rim 35 which is notched radially at 36. A relatively small spacing is formed between the lowermost edges of rim 35 and tray 28 as is well known in the art.

Referring now to FIGURE 3, a flared skirt 38, having slots 38a therein, extends radially outwardly and downwardly of tray 28. A Weir 39, having substantially V-cut notches 39a therein, extends circumferentially and vertically upwardly of tray 28 as seen in FIGURE 3. An opening 40 extends through tray 28 for reasons to be discussed hereinbelow. As can be seen in FIGURE 4, a plurality of lifting lugs 41, streamlined in the direction of flow of liquid over tray 28, is disposed on tray 28. As can best be seen in FIGURES 3 and 5, an underflow weir 42 extends circumferentially of tray 28 and has a plurality of downwardly extending substantially large notches 42a therein.

FIGURE shows the flow patterns for liquid introduced through distributor 32 onto tray 28. The liquid flows from pipe portion 31 (FIGURE 2) under notches 36, past lugs 41 under weir 42 and over weir 39 in the direction of the arrows. Notches 36 and 42a provide partial restriction of the liquid flow designed to provide essentially equal peripheral distribution of the liquid to weir 39.

Thus, in operation, the distilland issues from distributor 32 on the top surface of plate 28 at a point spaced materially inwardly from the extreme outer edge of the plate. As the distilland flows horizontally over the top face of plate 28, in a comparatively thin film, any gas remaining in the distilland is drawn off by the vacuum within chamber 11. This plate 28, therefore, constitutes a final degassing surface. As the distilland flows outwardly from distributor 32 (FIGURE 2) through notches 36 and towards the periphery of plate 28, it flows through notches 42a in underflow weir 42 and comes against the upstanding marginal weir 39 (FIGURES 3 and 4) extending around plate 28 on its outer edge and flows out through notches 39a in weir 39 which lead to slotted skirt 38. Slotted skirt 38 terminates very closely to the inner face of the evaporating wall 12 (FIGURE 1) and the fingers formed by slots 38a press against the wall 12 and distribute the liquid as a thin film through the slots 38a so that the distilland is applied thereto in a very favorable manner, flowing down the wall 12 at lower pressure and low velocity without substantial splattering or splashing.

Referring now to FIGURE 6, a pair of rows of overlapping, vertically supported U-shaped de-entrainer channels 43 form a cylindrical bafile skirt 44 disposed within 4 chamber 11 and surrounding a U-tube condenser 45 extending longitudinally of chamber 11 (FIGURE 7). The channels 43 are retained in a vertical upright position by conventional means, as for example, by a plurality of spaced de-entrainer spacer rings and rest on a ring (not shown) near the bottom of the vessel.

Referring now to FIGURE 7, condenser 45 includes a plurality of vertically extending tubes 47 disposed radially and secured together by conventional means such as a tube sheet within condenser head 21 and spaced cross baffies 50 and 46 (FIGURE 1). Tubes 47 are in staggered rows, and a pair of V-shaped longitudinal batfles 49 are mounted within tubes 47 diametrically opposite one another. Baflies 49 extend the full length of condenser 45 and are retained therein by conventional mounting means, such as by tie rods or by being Welded or otherwise fastened to cross baflles 46 disposed at spaced intervals along condenser 45 so as to provide for tube spacing and stability. Tubes 47 also extend through openings 50a in bafile 50 which is illustrated in FIGURE 9. The top cross bafile 50 is provided with a peripheral seal, such as a Teflon gasket 51, fastened thereto by bolt means 52. Gasket 51 serves to seal cross bafile 50 within the upper section of shell 19.

As can be seen in FIGURE 10, the tubes 47 on the first pair of inside rows have restriction orifices 48 so as to promote the desired flow of coolant through all the condenser tubes 47. The restriction orifices 48 reduce the flow of coolant to the inner rows of tubes where a smaller fraction of the distillate is condensed. The restriction orifices are provided to give water distribution which is in proportion to the expected heat transfer and thus gives approximately the same outlet water temperature.

Preferably all of the tubes 47 are of circular crosssection. Baflie channels 43 prevent free passage of entrapped liquid from the evaporating surface to the condenser surface and also reduces the heat loss from the evaporator to the condenser. The baflle channels 43 permit any vapors and entrapped liquid molecules attempting to pass from the hot evaporating surface inwardly towards the condenser to turn outwardly away from the center of the still, then inwardly towards the cold condensing surface. These abrupt bends greatly increase the chance that any molecule of distilland in liquid phase, entrapped inand traveling with the distilled vapors, will be projected against and come into contact with the channels 43 thereby stopping the travel of the molecules in liquid phase and preventing such undistilled molecules from reaching the condenser surface.

In addition to serving as traps for molecules in liquid phase, the channels 43 serve also as heat conserving means, impeding the otherwise wasteful flow of radiant heat from the hot evaporating surface 12 of the still to the cold condenser surface. The channels 43 are preferably of polished metal so as to reflect the radiant heat from the surface 12 back outwardly towards the surface 12, thereby greatly cutting down the heat loss from the evaporating surface.

In operation, as heating jackets 15 are heated by injecting steam through conduit 16, the vapors distilled off of the hot evaporating surface 12 of the still pass inward in a general radial direction towards the center of the still. The falling film has a substantially large vertical flow path in which vaporization takes place (i.e., the dimension L in FIGURE 1). The evaporated vapor, as discussed previously, leaves the wall horizontally and flowsinward over the internal condenser 45 and upward towards the vacuum outlet 27. Enroute, the vapor is deentrained through the channels 43 which reverse the vapors 180 and knock out any heavy ends and/or catalyst materials which then fall or flow down the channels 43 to a doughnut-shaped residue collector tray 23 (FIG- URE l) and from there to a residue outlet 54.

As can be seen in FIGURE 1, tray 53 slopes downwardly towards outlet 54 and is disposed directly below the lower end of channels 43. The cross bafile tube spacers 46 (and also the cross baflles) have upwardly extending outside drip lips 55 thereon. The cross baflle '57 has a configuration as shown in FIGURE 11 rather than the O-shaped con-figuration of the other cross baffles 46 (FIG- URE 1); cross baffie 56 has a similar but opposite configuration. This is to provide a battle for distillate flow to minimize splashing of liquid from the accumulated liquid in the collection area 63. Larger openings are re quired in the upper battles to minimize pressure drop of noncondensible vapor leaving through outlet 27. Baflles 20 and 50 are intended to provide maximum vapor cooling by forcing the vapor to the center where it must then pass four rows of tubes to exit at outlet 27.

The lowermost portion of the bottom member 14 is provided with a product outlet 58 retained therein by a flange 59 and plate 60 arrangement. A wear plate 61 is disposed directly above plate 60 and below tray 53 for keeping the liquid velocities from wearing the head too thin.

The lower end of condenser 45 is steadied in chamber 11 by a plurality of radially spaced guide plates 62, only two of which are shown in FIGURE 1 for convenience of illustration. Supported within chamber 11 directly below the lowermost portion of condenser 45 is a center surge or colletcion area 63 surrounded by the collector tray 53. Area 63 may be funnel shaped, if desired. Area 63 is a residue dam that serves as a barrier to prevent bottoms from flowing into the distillate collector.

In operation, the de-entrained vapor is condensed on the condenser 45 which contains a relatively large heat exchange surface area. The cooling medium is preferably tempered water so as to prevent the liquid, such as alcohol, from freezing on the exchanger tubes 47. The condensed liquid, such as alcohol, flows down the outside of the individual tubes 47 of condenser 45 and falls into the center surge or collection area 63 where it is drained off on gravity flow from product outlet 58 to an evaporator accumulator (not shown).

The evaporator bottoms residue from the evaporator chamber 11 is collected on the outside perimeter of the bottom member 14 and is drained on gravity flow along tray 53 to the outlet 54. If desired, a portion of the evaporator bottoms residue may be cooled and pumped in a return flow to serve as a quench and thus lower the residue outlet temperature so as to prevent excessive bottoms degradation due to residence time at the higher temperature.

The feed rate to the evaporator chamber 11 may be controlled by a conventional flow recorder controller in the feed line (not shown) to the inlet 31 actuating a feed flow control valve (also not shown).

The split between product and residue in chamber 11 has been found to be normally about 70/30. This is caused by the temperature on the evaporating surface 12. This temperature increases down Wall 12 due to the fact that there is a different steam pressure in each jacket 15 which increases down the chamber 11. For example, the steam pressure in the top jacket 15 may be about 24 p.s.i.g. whereas the steam pressure in the bottom-most jacket will be about 47 p.s.i.g. These pressures exist when the evaporator walls 12, 13, and 14 are clean; however, experiments have shown that they will become progressively higher as the evaporator walls 12, 13, and 14 become fouled with decomposition products.

A spray inlet 64 (FIGURE 1) may be provided for cleaning the interior evaporator surface of chamber 11. Inlet 64 passes through opening 40 in tray 28 and includes a spray cleaning manifold ring 65 having a plurality of spaced spray heads 66 for spraying the interior wall 12 and channels 43. For example, if stainless steel is used for the internal equipment of chamber 11, nitric acid solution may be used as the cleaning agent to remove the deposit.

Variances in steam pressures through jackets 15 may be used to set up a temperature gradient along the flow of liquid down the evaporator wall 12. The temperature in the bottom member 14 may be maintained at a desired value by proper adjustment of the steam pressures. The steam pressures can be adjusted in the jackets to approximate a constant temperature difference between the jacket and the liquid on the wall.

In operation, for economy reasons, a plurality of evaporator chambers 11 may be used. In this manner, a block valve in a combined vacuum line from any given set of two evaporators may be closed, therefore enabling isolation of any set of evaporators for maintenance or cleanout.

The still walls, condenser and all other parts coming into contact with the distilland or its vapors are preferably made of some suitable metal, such as stainless steel or steel faced with glass, which is resistant to corrosion by the distilland and the preferred cleaning solution.

The present invention in all of its aspects is applicable to the distillation of hydrocarbon oils, fruit juices, synthetic organic liquids, especially those which readily decompose, and is especially adapted for vacuum distillation in which the entrainment of non-vaporized residual droplets of liquid presents a problem. It will be obvious to one skilled in the art in possession of this disclosure that various other distillable materials can be distilled employing the apparatus of the invention.

We claim as our invention:

1. Apparatus for distilling a liquid whichis adapted to be distilled into vapor, heavy residue and liquid components comprising:

a chamber formed in said apparatus;

an elongated shell having an internal wall substantially vertically disposed within said chamber;

stationary liquid distributing and degassing means in substantial contact with said internal wall adapted to flow said liquid in a relatively thin film down the wall of said shell under the influence of gravity while drawing off any gas in said liquid;

said liquid distributing means including a liquid inlet conduit associated with the upper portion of said chamber above said shell;

2. liquid distributor tray substantially horizontally disposed within said chamber and in close proximity to said wall;

liquid dispersing means associated with both said conduit and said tray for dispersing said liquid in an agitated state on said tray;

heating means cooperating with said wall for heating any liquid flowing down said wall;

a condenser coaxially disposed within said chamber;

vapor component outlet means associated with said condenser for withdrawing any evaporated vapor components from said chamber;

stationary de-entraining means disposed between said wall and said condenser adjacent substantially the entire length of said internal wall for de-entraining any entrained residue components in the vapors which emanate substantially horizontally from said heated wall towards said condenser and adapted to turn any vapors and entrapped liquid molecules passing from the wall of said shell towards said condenser approximately outwardly from the center of said chamher then inwardly towards said condenser so as to prevent any undistilled entrapped liquid molecules from reaching said condenser;

residue components outlet means associated with said de-entraining means for removing said entrained residue components from said chamber; and

condensed liquid components removal means associated with said condenser for removing any condensed liquid components flowing down said condenser.

2. The apparatus of claim 1 wherein said tray includes:

a downwardly and outwardly extending peripheral flared skirt having a plurality of slots therein in close proximity to said wall;

7 8 a substantially vertically upwardly extending wall havits lower end, with the lower end of said pipe being ing a plurality of notches at its upper end extending spaced a short distance above the slots which extend peripherally of said tray; and about the lower periphery of the pipe of relatively said wall further including a plurality of spaced slotted large diameter.

portions opening downwardly at its lower end, said 4. The apparatus of claim 1 wherein said de-entraining slotted portions forming fingers pressing against said means include a plurality of interlocking vertically suswall, the areas directly above said slotted portions pended substantially U-shaped channels disposed in a being free from said notches. substantially circular array about said condenser. 3. Apparatus for distilling a liquid which is adapted 5; The apparatus of laim 4 wherein said circular to be distilled into vapor, heavy residue and liquid com- 10 array consists of a pair of rows of said channels. ponents comprising: 6. The apparatus of claim 1 wherein said condenser achamber formed in said apparatus; includes a plurality of staggered rows of vertically exan elongated shell having an internal wall substantially tending condenser tubes;

vertically disposed within said chamber; coolant inlet and outlet means communicating with said stationary liquid distributing and degassing means in tubes for flowing coolant into and out of said tubes; substantial contact with said internal wall adapted substantially horizontally extending cross baflle means to flow said liquid in a relatively thin film down said having upstanding peripheral lips being disposed at wall under the influence of gravity; spaced intervals along said tubes for deflecting said heating means cooperating with said wall for heating liquid;

any liquid flowing down said wall; substantially vertically extending V-shaped baffle means a condenser coaxially disposed within said chamber; disposed between the rows of said tubes for deflectvapor component outlet means associated with said ing the vapor; and

condenser for withdrawing any evaporated vapor some of said tubes having an inlet orifice for providing components from said chamber; distribution of said coolant. stationary de-entraining means disposed between said 7. The apparatus of claim 1 wherein said residue comwall and said condenser for de-entraining any enponents outlet means is disposed directly below the lower trained residue components in the vapors which end of said de-entrainer means; emanate substantially horizontally from said heated said condensed liquid components removal means is wall towards said condenser; disposed directly below the lower end of said conresidue components outlet means associated with said O denser;

de-entraining means for removing said entrained said residue components outlet means surrounding said residue components from said chamber; condensed liquid components removal means being condensed liquid components removal means associated in a sealed-01f relationship with said liquid comwith said condenser for removing any condensed ponents removal means; and liquid components flowing down said condenser; said vapor components outlet means being disposed said liquid distributing means including a liquid inlet at the top of said chamber and in communication conduit, a liquid distributor tray substantially horiwith the upper portion of said condenser. zontally disposed within said chamber and in close 8. The apparatus of claim 1 including spray inlet proximity to said wall, and a liquid dispersing means means associated with the interior of said chamber for associated with both said conduit and said tray for introducing a spray of cleansing material into said dispersing said liquid in an agitated state on said chamber. tray; said tray including a downwardly and outwardly ex- References cued tending peripheral flared skirt having a plurality of UNITED STATES PATENTS slots therein in close proximity to said wall, a sub- 2,180,052 11/1939 Hi k t 1, 202 236 stantially vertically upwardly extending wall having 2,353,551 7/ 1944 D t r 202-236 a plurality of notches at its upper end extending 2,793,174 5/1957 Smith 202236 peripherally of said tray, and said wall further in- 2,901,425 8/1959 Waddill 202-236 eluding a plurality of spaced slotted portions opening 2,938,866 5 /196() Engel t a], 202 236 downwardly at its lower end, the areas directly above 2,956,934 10/1960 Waddill 202-197 said slotted portions being free from said notches; 3,004,901 10/1961 Nerge et a1. 202-236 and 3,054,729 9/1962 Smith 202-236 said liquid dispersing means including an inlet pipe of 3,234,108 2/1966 Hull 202--236 relatively small diameter secured within a pipe of relatively large diameter, with said inlet pipe being W -B R L. BASCOMB, J R., Primary Examiner in communication with said liquid inlet conduit, and said pipe of relatively large diameter being spaced a short distance above said tray and having aplurality 55-41, 159l3; 202-487, 197, 205, 236, 241;

of spaced slots extending about the periphery of 20389, 90, 99 

